Feeding Your Soil: Creating a Soil Food Web
Here in the South, where I live, spring is in full bloom. While transplanting my seedlings into the cool ground, I dig my hands into the soil, breathe in the sweet earthy aroma and I am revived. It feels like magic and, in a way, it is.
Healthy soil is just bursting with life. Just a handful of that dark, crumbly substance has more living organisms than there are people on the planet. The biology in the soil is a beautiful illustration of the web of life. These macro and microorganisms are part of an underground ecosystem. Synergistic relationships are formed between the roots of the plants and the soil life surrounding them. This area of activity is called the rhizosphere. It is essential that these relationships exist and we should nurture them in our gardens and landscapes. If we do, we can enjoy healthy soil and plants, leading to healthier animals and humans.
Simply put, plant roots release sugars, proteins and carbohydrates that feed the beneﬁcial bacteria and fungi in the soil. These are called root exudates. In return, these microorganisms inhibit and consume pathogenic and parasitic elements in the soil. The fungi collect water and phosphorus, and form a communication network between plants. Bacteria and fungi take up inorganic minerals present in the soil and serve as food for predatory species like protozoa and nematodes, or worms and millipedes. The latter consume the bacteria and fungi, releasing waste nutrients that have been transformed into a soluble form plants can use.
Letʼs look at a few ways we can support and enhance soil life. The key is to think of these organisms as subsurface animals, or micro-herds. These micro-herds need to be given a proper environment to thrive, just like any other type of living creature.
Organic matter and compost will help you breed and feed the soil food web. I have found that composting right in the garden is an excellent way to feed the soil. Now, donʼt run out and put last night’s dinner in your garden or you will invite all types of unwanted guests. One way to compost in place is to leave the plant roots after a harvest. As the roots break down, little tunnels remain for air and water to penetrate the soil, much like the ones an earthworm leaves. When you are done harvesting, rather than pulling out the whole plant, cut it off level with the soil and cover with mulch. Sometimes I leave whole daikon roots in the soil to break down leaving behind a forearm’s worth of organic matter. Another way is to take the stalks of spent plants, if they are disease-free, and put them under the mulch. I also do this with plants that accumulate nutrients, like comfrey and legumes. Any weeds will work, too. If you are afraid they may re-root, just let them dry out a few days before placing under the mulch. The organisms will devour all plant residue and release the nutrients.
Compost and compost tea can be custom-made to be fungal or bacterial dominated. Different species beneﬁt from different balances. Brassicas prefer a highly bacterial environment, most veggies like moderately bacterial, berries and perennials like a balance of bacteria and fungi, deciduous trees thrive with moderately fungal and coniferous prefer high fungal. Bacteria like fresh green matter and a lower carbon:nitrogen ratio, while fungi like woody, more ﬁbrous material and a higher carbon:nitrogen ratio. To ensure the presence of fungi, inoculate by adding some soil from a healthy woodland or with endomycorrizal fungi from a reputable dealer. I dust the roots or seeds of most of my vegetables and all my perennials with inoculant before planting.
The soil food web will thrive with green manures, cover crops, plenty of diversity, mulching, the addition of organic matter and avoidance of tillage. Tilling shreds fungal networks and repeat tilling will burn out microbes. Kelp meal will stimulate microbial activity and biochar can provide surface area used as a habitat for the microorganisms. More information and testing can be found at SoilFoodWeb.com. A great resource for compost and teas is CompostJunkie.com.
If you are not running outside to feed your soil, you should be. These practices combined with remineralization, as discussed in part 1, will lead to increased yields, reduced water use, disease and pest resistance, better soil structure and more nutritious food. Not to mention the bacteria induced mood enhancers you receive when digging your hands in the dirt.
See? Nothing short of magical.
What do you do to keep your soil well-fed?
Photo Credit: Craig McCord
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